The pressure. The pounding. The pain. You know the symptoms. You’ve got a headache. What you might not know are some of the surprising causes for your headache. While there are a many different types of headaches, such as cluster, sinus, migraine and chronic, the most common is a tension headache. The pain is usually mild to moderate, steady and can feel like a band of pressure squeezing around your head. Stress, anxiety and depression can all lead to tension headaches, but so can a surprising number of other triggers. Are any of these sneaky culprits causing your headaches?

1. An Incorrect Eyeglass Prescription

Wear contacts or glasses? If your prescription is too strong, it may cause your eyes to strain and give you a headache, says David Shapiro, M.D., director of the Shapiro Laser Eye Center. This overcorrection can happen during the refraction test where your optometrist shows you two letters and asks you if option one or two is better. “The overcorrected choice can be more appealing because it can look darker or bolder,” says Dr. Shapiro. “But if the correction is too strong," he says, "the lens needs to bulge and squeeze constantly.” All this squeezing can lead to headaches. Fortunately, they'll go away with a prescription correction.

2. A Too-Tight Ponytail

Always wearing an updo at your job or during your workout? You may find that your hair clips or too-tight ponytail can lead to a headache. “I’ve had long hair all my life, and sometimes bobby pins or other types of hair clips can give me mild headaches,” says freelance writer Carrie Aulenbacher. When the hair is pulled taut, it puts constant pressure on the connective tissue in the scalp until you take your hair down. The same pain can also occur with a tight headband, headphones or braids. Try loosening your braid or ponytail or limiting your use of these hairstyles.

3. An Overloaded Bag

Any activity that causes your head to be in the same position for a long time can cause a tension headache. A culprit you might miss? Your overloaded purse or backpack. “Different types of bags, and the ways they are carried affect people’s posture,” says Karena Wu, a physical therapist and clinical director of ActiveCare Physical Therapy. “When we don’t practice good posture, the imbalances created in the muscles cause pain, dysfunction and altered mechanics that eventually lead to injury.” Try limiting how much weight you carry in your bag and regularly switching carry shoulders.

4. Your Headache Medication

Ready for some painful irony? If you're regularly popping pills to deal with your headaches, you could be causing yourself more head pain, says Mark Khorsandi, D.O., founder of the Migraine Relief Center. “Medication overuse can actually trigger the headaches they’re trying to solve,” says Dr. Khorsandi. Called “rebound headaches,” these headaches are often felt in the morning and can occur with regular use of a wide range of over-the-counter medications. “We usually advise stopping the medication if the rebound headache occurs, but this can create withdrawal symptoms for up to a week. Finding the right balance of medication can stop this problem.”

5. Jaw Clenching

If you regularly wake up with a morning headache, jaw clenching (bruxism) might be to blame. While it can also happen during the day, many people who grind or clench at night are not aware that they do it. “What we don’t realize is that when we actually get a chance to wind down, relax and, more importantly, sleep, our brains are often working overtime and subconsciously do not stop,” says Zafar Khan, principal dentist at Horsforth Smile Clinic. Addressing the clenching with a mouth guard and a better wind-down routine at night can help reduce the grinding and ensuing headaches.

6. Cradling a Phone

Cradling a phone to your ear may be an easy way to stay hands-free on a call, but it could also be causing your headaches. “If a person is cradling a phone, the two most common muscles that become shortened, tight and irritated are the upper trapezius and levator scapulae,” says chiropractor Erik Korzen. “And tightness in both of these muscles can lead to tension headaches.” Switching sides, using a headset and integrating stretching and massage can help to prevent this upper-shoulder tension.

7. Sleep Apnea

Sleep apnea is characterized by loud, chronic snoring, often with pauses, choking or gasping. Another symptom? Headaches. “Sleep apnea is a common cause of headaches that often goes unnoticed,” says Jared Heathman, M.D. During repeated breathing pauses throughout the night, carbon dioxide has the chance to build up in the blood, causing headaches, memory problems and mood changes. “Those that suffer from frequent headaches and snoring should consider meeting with a sleep specialist to be properly evaluated,” says Heathman.

8. Dehydration

“One of the easiest ways to get a headache is from dehydration,” says Matt Tanneberg, a sports chiropractor. According to the U.S. National Library of Medicine, the average person needs about three quarts of water a day -- more if it’s hot outside or you’re exercising. Since the brain is composed of nearly 75-percent water, its functions depend on being hydrated. Among other problems, if you haven’t consumed enough water you can experience headaches. Dehydration can also be caused by consuming too much alcohol or consuming too much salt. Make drinking water during the day a priority, and if you feel a headache coming on, start with a glass of water before reaching for pain medication.

What Do YOU Think?

Do you regularly get headaches? What do you do to treat them? Do you know what’s causing your headaches? Is it any of the things on this list? Did you find any of these things surprising? What other unusual causes of headaches have you encountered? Share your thoughts, stories and questions in the comments below!

Left-Sided Headache After Workouts

The pressure. The pounding. The pain. You know the symptoms. You’ve got a headache. What you might not know are some of the surprising causes for your headache. While there are a many different types of headaches, such as cluster, sinus, migraine and chronic, the most common is a tension headache. The pain is usually mild to moderate, steady and can feel like a band of pressure squeezing around your head. Stress, anxiety and depression can all lead to tension headaches, but so can a surprising number of other triggers. Are any of these sneaky culprits causing your headaches?